Huh, that's funny. Looks like it's only affecting me for some reason. I have no idea why. I literally cannot move any fleet with ramjets in it, it just comes up with a "unable to plot a course" error. Even if the world I'm selecting as the destination is right next to the ramjet yard. Oh well, I guess we can just say the Imperium lost ramship tech long long ago and never recovered it...

"Live long and may the Force be ever in your favour, Mr. Potter"
-- Gandalf (The Chronicles of Narnia)

Okay, since I've expanded into the light nebula south of me I can confirm ramjets are indeed working properly. It seems to be just that little strip of dark nebula surrounding my capital that's acting funny. I think the ramjet code is thinking it's a rift zone instead of a nebula so it's refusing to path ships through it, IDK.

"Live long and may the Force be ever in your favour, Mr. Potter"
-- Gandalf (The Chronicles of Narnia)

This doesn't have much to do with Ramjets, but in respect to the dark nebula code maybe thinking it is a rift zone there are patches of rift zone that have been taken over by dark nebula, a fleet may pass through the rift zone normally in this case. Perhaps they are related.

I'm fairly certain it is not normal for the rift zone, turned dark nebula, to be passed THROUGH from one place to the next, as though the the rift zone no longer is there. But these were jumpships not ramjets, I don't have any to try it with.

I have recently run into this bug as well. I bought some hammerheads at a mesophan world in the dark nebula in my northeast sector and was unable to tell the fleet to go anywhere at all, from next door planet to ways away. None were trying to path around rift zones, should have been direct flights from planet to planet.